Most parts are easily available and non critical – in most cases value can be substituted for something close to hand.
LCD is available from ebay, or can be purchased via Farnell (or RS Components) for slightly more cost, stick to the aprox size shown below to make sure the mounting holes match the pcb. Other sizes will work – but you’ll have to handle the mechanics of bolting things together differently.
Keypad can be any arrangement of 4x4 buttons. Farnell keypad (also available via RS) is expensive but allows the buttons to have customisable legends).
I’ve broken the parts list into 3 parts, Basic, beeper and sense/ack.
Basic parts provide the basic working controller. Beeper and Sense/Ack are optional.
Beeper adds parts required for the key beep feedback.
Sense/Ack provide the parts to allow the controller to communicate with other equipment.
Note: If you don’t add the Sense/Ack circuitry connect pin 2 of IC1 to gnd via a 10k resistor.
Basic:
Part Number
|
Qty |
Value |
Notes |
C1, C2 |
2 |
33pF |
|
C3, C4 |
4 |
100nF |
Decoupling – spread liberally. |
C5 |
1 |
470uF |
|
VR1 |
1 |
10k Preset |
Contrast control |
R1, R2, R3, R4 |
4 |
10k |
Keypad pull downs |
IC1 |
1 |
18F452 |
Pre-programmed with firmware. |
IC2 |
1 |
7805 |
And small heatsink. |
40 pin IC Socket |
1 |
|
For PIC 18F452 |
Xtal |
1 |
10Mhz |
|
Keypad |
1 |
4 x 4 Matrix |
Farnell 1171224 (or 16 buttons…) |
LCD |
1 |
4line x 20column HD44780 compatible |
Available for around £5 on ebay. (Aprox size 97mm x 59mm, view window 76mm x 25mm). |
PCB |
1 |
|
Or stripboard construction. |
8 Pin SIL socket |
1 |
|
Only if using Farnell keypad. |
Connector |
1 |
4 pin 2.54 pitch |
Can solder wires instead. |
Case |
1 |
|
To suit (case I used is Farnell 775-319) |
Power supply |
1 |
8 – 30v |
To suit stepper/stepper controller. If using typical 2A stepper then a 24v laptop psu is ideal. If stepper controller has own supply then any small DC wall-wart will do. |
LS1 |
1 |
Passive sounder |
Passive sounder of the type fitted to computer motherboards. |
Q3 |
1 |
BC337 |
NPN transistor (500mA IC) |
R5 |
1 |
4k7 |
|
D2 |
1 |
BYV27 |
Any fast switch diode |
D1 |
1 |
BYV27 |
Any fast switch diode |
Q1, Q2 |
2 |
BC337 |
NPN transistor (500mA IC) |
R8, R9 |
2 |
4k7 |
|
R6, R7, R10, R11 |
4 |
10k |
|
Connector |
1 |
5/6 pin 2.54 pitch |
Can solder wires instead |